Steering Angle Determination Using Relative Rotation Sensor
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Solution Overview
Problem
Existing methods for determining the steering angle in motor vehicles rely on absolute angular positions, which are prone to errors and do not accurately account for initial shaft positions, limiting their effectiveness in systems like vehicle stability assist.
Innovation Solution
A method that sets a relative steering angle to an initial value upon ignition, updates it based on rotation sensor data, and resets it upon subsequent ignition, allowing for continuous calculation of the steering angle offset during stable driving conditions to adjust the steering angle accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If absolute angular position sensing methods are used to determine steering angle, then the steering angle can be determined relative to a center position, but measurement errors occur and accuracy deteriorates due to not accounting for initial shaft positions
Solution Approach 1:
The system performs preliminary calibration at ignition to establish the initial shaft position as the reference zero point before normal operation begins. This preliminary action ensures that subsequent steering angle measurements are based on the actual initial position rather than an assumed center position, eliminating cumulative errors.
Solution Approach 2:
The system changes the reference parameter from a fixed center position to a dynamic initial position that is determined at each ignition event. By adjusting the reference frame based on actual operating conditions, the system adapts to variations in shaft positioning and maintains measurement accuracy throughout the vehicle's operation.
2Device complexity
If stored values or known absolute reference positions are used for determining steering angle, then the calculation process is simplified, but errors accumulate and accuracy deteriorates over time and across ignition cycles
Solution Approach 1:
The system performs preliminary calibration at ignition to establish the initial shaft position as the reference zero point before normal operation begins. This preliminary action ensures that subsequent steering angle measurements are based on the actual initial position rather than an assumed center position, eliminating cumulative errors.
Solution Approach 2:
The system uses the vehicle's own ignition events and operational cycles to automatically recalibrate and reset the reference position without external intervention. Each ignition event triggers a new calibration sequence that self-corrects any accumulated errors, making the system self-maintaining over time.
3Measurement precision
If the steering angle reference is reset at each ignition event, then accuracy is maintained for each operating cycle, but the system requires continuous calibration and becomes more complex
Solution Approach 1:
The system performs calibration periodically at each ignition event rather than continuously during operation. This periodic reset approach maintains accuracy for each operating cycle while avoiding the complexity of continuous calibration systems, as the reference is established only when the vehicle starts and then maintained throughout normal operation.
Data Source
AI summary
A method for determining a steering angle of a steering shaft in a motor vehicle is disclosed. The method uses a rotation sensor associated with an electric motor of a power steering system to determine the relative steering angle of the steering column. The relative steering angle is measured relative to an initial position of the steering column during vehicle startup. The relative steering angle is reset each time the motor vehicle is turned on.